In our prior international patent application PCT/AU99/00918 relating to “Sampling in Blood Collection”, we disclosed valve means whereby the first portion of blood collected from a donor could be diverted for sampling before the blood line was connected to the blood collection pouch. An important feature of such valve means is that, once sufficient blood has been diverted for samples, connection to the diversion tube must be permanently closed to be absolutely sure that no contamination from the diversion tube can find its way into the blood collection line to the collection pouch. The valve means disclosed in our prior application was fool-proof in the sense that the collection line could not be opened before the diversion line had been securely closed and that, once closed, the diversion line could not be re-opened or re-connected. This arrangement allowed samples to be drawn off from the diversion line using a sample port and vacuum vial before blood collection commenced.
An important reason for wishing to divert blood for sampling during blood collection is that any skin plug that is cut and retained by the needle can be washed out into the diversion or sample line rather than into the main collection pouch. It is thought that such skin plugs are responsible for much of the bacterial contamination of collected blood pouches.
In an alternative method of ‘sampling first’, the initial flow of blood is diverted to a sealed sample bag while the blood line to the collection pouch is temporarily blocked, after sufficient sample blood has been collected, the tube to the sample bag is blocked and the tube to the pouch is opened. If desired, samples can be drawn off from the sample bag while blood collection continues. This system is not fool-proof in that manual clamps are used to block the diversion tube and the main blood line. They can be operated in the wrong sequence or the clamp on the diversion line can either be re-opened or not properly closed.
In the collection of blood from donors, or when handling blood or other IV liquids in flexible tubing, one-piece molded-plastic pinch clamps are often used to control fluid flow in the tubes because they are cheap and disposable. In some such situations it is important that the clamps cannot be re-opened after having been finally closed to seal a tube.
The tube clamp with which the present invention is concerned is of the type that comprises a one-piece generally C-shape plastic molding having a pair of opposed jaws joined by a flexible hinge portion and that is adapted to fit onto a flexible plastic tube so that the tube passes between the jaws, whereby the flow of fluid through the tube is permitted when the jaws are open but is blocked when the jaws are brought together to pinch close the tube there-between. This type of tube clamp normally includes releasable locking means that allows the jaws to be clipped together in the closed position.
In blood collection procedures where many donors and blood packs are handled by a single phlebotomist in an hour, it is also important that the clamp be easy to lock closed, that any locking tabs or the like do not protrude so as to be likely to tear or puncture surgical gloves, poke into the user's thumb or fingers or to snag medical dressings, clothing or other fabric. It is also desirable that there is auditory and/or visual confirmation of proper closure. Preferred embodiments of the invention provide a device that satisfies at least some, if not all, of these requirements.